Sandal upper



FIG. 1 is a top perspective view of a sandal upper embodying my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a right side elevation view thereof; and,

FIG. 6 is a left side elevation view thereof.

Features shown in dashed lines are for environmental purposes and do not form a part of the claimed design. 

The ornamental design for a sandal upper, as shown and described. 